In such carriages, the eggs are generally placed in cradles which are superposed in columns, with the carriage comprising a plurality of juxtaposed columns which are generally assembled in such a manner as to form a wheeled assembly.
In order to obtain proper incubation, the cradles in the various columns are capable of being tilted back and forth in both directions.
During incubation, the cradles are tilted to about 40.degree. to 50.degree., and they are moved at intervals of one to three hours.
Incubation carriages generally comprise three to five columns each having 10 to 15 stages each of which receives cradles for 100 to 150 eggs to be incubated.
The carriages used in the past have been of the structure shown in FIGS. 1a and 1b, which shows a carriage 10 including a series of superposed egg-receiving cradles 11 disposed in a plurality of columns 13 mounted on a wheeled carriage 14.
The various cradles within a given column are interconnected at each end by risers 15, and the risers 15 are hinged at their top and bottom ends to tiltable crossbars 16 and 17, thereby enabling the assembly to be given the structure of a hinged parallelogram.
The top crossbars 17 are mounted on pivoting shafts 18 which are interconnected by a link 19. Thus, by moving the link 19 in reciprocating translation (arrow 20) it is possible to cause the shafts 18 to pivot together (arrows 20'), with all of the shafts pivoting identically, thereby causing all of the cradles in the carriage to be tilted simultaneously, as shown in FIG. 1b.
As can be seen in FIG. 1b, when the cradles are tilted, the various columns are separated leaving empty passages between the columns.
Such empty passages have the effect of disturbing the ventilation of the carriage: ventilation is performed, in particular, by a turbine system which establishes a pressure reduction, thereby setting up a flow of air through the carriage, with the direction of this air flow being substantially parallel to the shafts 18. When the cradles are all horizontal, the air flow splits up substantially uniformly over the entire mass of eggs to be incubated, whereas when the cradles are in the tilted position, the air flow tends preferentially to occupy the empty passages created between the columns, thereby reducing the ventilation volume passing through the mass of eggs to be incubated which set up a greater head loss through the columns themselves.
The prior art system therefore does not provide uniform and constant ventilation of the mass of eggs while they are being incubated.
One of the objects of the present invention is to remedy this drawback by proposing a carriage structure which maintains uniformity of ventilation through the mass of eggs to be incubated by preventing the columns from separating when the cradles are tilted.